The present invention relates in general to air ducts for automotive heating, ventilating, and air conditioning (HVAC) systems, and, more specifically, to forming an air duct inside a structural body member of an automotive vehicle.
In a typical automotive HVAC system, a main blower with one or more small auxiliary blowers are used to create a climate system air flow. The air flow is directed by concealed ducts to various registers in the passenger cabin. For example, the air flow may be directed to a general region of the cabin (as with a floor register), directly onto a passenger seating position (as with a dashboard register), or onto the glass windows for defogging.
The packaging of ducts within the available interior space can be a challenge. For example, it may be desirable to direct an air flow from above the bottom base line of the windows (i.e., from a location above the upper edge of the doors or instrument panel) either for the purpose of defogging the window glass or to provide a direct cooling air flow onto the face of a passenger. Conventional ducts have often been installed as distinct elements on the outside of the body frame or other structural elements such as a roof pillar. The duct is then covered with a finishing trim piece to conceal it when passing through visible areas such as a roof pillar of a door sill. However, thinner roof pillars are often desirable for styling purposes. Thus, improved vehicle styling, overall weight reduction, and efficient use of packaging space can be achieved by placing an air duct inside the hollow interior of a roof pillar.
A typical roof pillar or other structural member that could serve to contain an air duct may be typically made of stamped or hydroformed metallic bodies. Such metallic bodies have insufficient heat insulative properties to be used as HVAC ducts. Inserting a prefabricated air duct into a formed structural member may be impractical due to the irregular shapes of the structural member and due to the additional labor that would be involved. It is also known to apply an insulated coating to the interior of a structural member in order to convert a structural member such as a roof pillar into an HVAC duct. However, the use of coatings has had limited success because of limitations relating to the forming of a coated structural member, requirements for expensive materials and/or processing, and an inability to partition off only a portion of the structural member for use as a duct.